Australian Mark Webber left it late to top the times for Red Bull on Saturday evening's final free practice ahead of this weekend's Singapore Grand Prix. The 35-year-old Australian, watched from the pits by his father Alan, clocked a fastest lap time of one minute 46.081 seconds round the floodlit Marina Bay street circuit. His time was two-hundredths of a second faster than second-placed rival Briton Jenson Button of McLaren, the 2009 champion, who recovered splendidly from a frustrating Friday to reproduce his best form. Championship chasing German Sebastian Vettel, in the second Red Bull, was third fastest after failing to find an outstanding clear lap in the closing seconds of the session on soft tyres. This left him ahead of his nearest championship rival, two-time champion Spaniard Fernando Alonso of Ferrari, with Briton Lewis Hamilton, the 2008 champion, down in fifth in the second McLaren. Defending title-holder Vettel can clinch the title on Sunday if he wins and Alonso is off the podium. The session was run in steaming heat with a temperature of 35 degrees Celsius and humidity levels of 68 percent. German Nico Rosberg was sixth fastest ahead of his Mercedes team-mate and compatriot seven-times champion German Michael Schumacher, 42, with Brazilian Felipe Massa eighth in the second Ferrari. Japanese Kamui Kobayashi was ninth for Sauber ahead of German Adrian Sutil in a Force India car. The Saubers were fast in the opening laps before Button went quickest, only to be replaced by a sequence of drivers including Rosberg and Vettel. Button regained the top spot again, before Webber laid down his marker in the final minutes. Schumacher's best hopes were dashed when he was blocked by Venezuelan Pastor Maldonado of Williams -- not the first time this season that the Latin American has been in similar trouble. The incident saw the German pit after raising a red-gloved fist at his tormentor. Hamilton also had a difficult session and had to make use of an escape road when he locked up while pushing to find greater performance in his car.